var uname = new String("zhangsan");
uname = "lisi";
// 属性
console.log(uname.constructor);
console.log(uname.length);
// 方法
console.log(uname.charAt(1));
console.log(uname.charCodeAt(1));
console.log(uname.concat(" good"));
console.log(uname.indexOf("s"));
console.log(uname.lastIndexOf("s"));
// 比较字符串，返回数字，相同为0
var index = "zhangsan".localeCompare("zhangsan ");
console.log("index:" + index);
var str3 = "again ain gain";
var n = str3.match("/ain/g");
console.log("正则匹配:" + n);
var reg = /(\w+)\s(w+)/;
var str4 = "ali sara";
// 注意这里是 “$2 $1” 交换
var newStr = str4.replace(reg, "$2 $1");
console.log(newStr);
// 按正则搜索是否包含 ali，不包含返回 -1
console.log("是否包含ali:" + str4.search(/ali/));
// 切片
console.log(str4.slice(0, 2));
// 可以指定分割的数量，比如1
console.log(str4.split(" ", 1));
console.log(str4.substring(0, 1));
console.log(str4.toLocaleLowerCase());
console.log(str4.toLocaleUpperCase());
console.log(str4.toLowerCase());
console.log(str4.toUpperCase());
console.log(str4.toString());
console.log(str4.valueOf());
console.log(typeof str4.valueOf());
